Peelable, biaxially oriented polyester film

Abstract

The invention relates to a coextruded, peelable, and biaxially oriented polyester film with a base layer (B) and with at least one outer layer (A) applied to this base layer (B). The outer layer (A) is heat-sealable and features good peelability with respect to nonpolar substrates, such as polystyrene and polypropylene. The heat-sealable and peelable outer layer (A) includes a copolymer of ethylene and polar-ethylene. The invention further relates to a process for the production of the film and to packaging formed from the film.

1 . A multilayer, coextruded, biaxially oriented, sealable, polyester film comprising a base layer (B) and a heat-sealable outer layer (A) peelable with respect to polystyrene (PS) and polypropylene (PP), wherein
 a) the heat-sealable and peelable outer layer (A) is comprised mainly of a composition comprising
 from 30 to 95% by weight of ethylene-polar-ethylene copolymer, and 
 from 5 to 70% by weight of polyester, 
 where the proportion of polar-ethylene in the ethylene-polar-ethylene copolymer is from 12 to 50 mol %, 
   b) the thickness of the outer layer (A), d A , is from 2.0 to 20 μm, and   c) the outer layer (A) comprises particles whose average diameter is from 2.5 to 15 μm and whose concentration is from 0.5 to 10% by weight, based on the outer layer (A).   
     
     
         2 . The polyester film as claimed in  claim 1 , wherein the base layer (B) comprises a thermoplastic polyester. 
     
     
         3 . The polyester film as claimed in  claim 2 , wherein the polyester of the base layer (B) contains at least 90 mol % of ethylene glycol units and terephthalic acid units or ethylene glycol units and naphthalene-2,6-dicarboxylic acid units. 
     
     
         4 . The polyester film as claimed in  claim 2 , wherein the polyester of the base layer (B) comprises polyethylene terephthalate. 
     
     
         5 . The polyester film as claimed in  claim 1 , wherein, in the sealable outer layer (A), the proportion of ethylene-polar-ethylene copolymer is from 35 to 90% by weight, and the proportion of polyester is from 10 to 65% by weight. 
     
     
         6 . The polyester film as claimed in  claim 1 , wherein the sealable outer layer (A) further comprises SiO 2  particles as pigment. 
     
     
         7 . The polyester film as claimed in  claim 1 , wherein the thickness of the sealable outer layer (A) is from 2.0 to 20 μm. 
     
     
         8 . The polyester film as claimed in  claim 1 , wherein the minimum sealing temperature of the sealable outer layer (A) with respect to PS and PP is 150° C. or lower. 
     
     
         9 . A process for producing a coextruded polyester film as claimed in  claim 1 , comprising the steps of
 a) producing a multilayer film by coextrusion,   b) biaxially stretching the coextruded film, and   c) heat-setting the biaxially stretched film,   
       wherein the polyester film comprises a base layer and at least one heat-sealable and peelable outer layer (A), and the heat-sealable and peelable outer layer (A) is comprised mainly of a composition comprising from 30 to 95% by weight of ethylene-polar-ethylene copolymer and from 5 to 70% by weight of polyester, and the proportion of polar-ethylene in the ethylene-polar-ethylene copolymer is from 12 to 50 mol %, and the outer layer (A) further comprises particles whose average diameter is from 2.5 to 15 μm, said particles present at a concentration of from 0.5 to 10% by weight, based on the outer layer (A). 
     
     
         10 . Food or other consumable item packaging comprising a film as claimed in  claim 1 . 
     
     
         11 . Food or other consumable item packaging as claimed in  claim 10 , wherein the food packaging is packaging for dairy products in pots.